This invention relates to a method for treating aqueous solutions of calcium abundant soybean protein and more particularly, to a method for treating aqueous solutions of calcium abundant soybean protein so as to prevent the precipitation of the soybean protein in the solution due to the addition of calcium to the solution to thereby preserve a high calcium concentration in the soybean protein.
Aqueous solutions of soybean protein represented by bean soup have been the object of attention as a drink containing excellent vegetable protein in an abundant amount in the art. However, aqueous solutions of soybean protein generally contain calcium in a less amount than milk and the insufficient calcium concentration is a nutritive disadvantage of the aqueous solutions of soybean protein.
In order to make up for the deficiency of calcium in the bean soup, when the bean soup is added thereto calcium salt in an amount sufficient to increase the calcium concentration in the bean soup to the same calcium concentration as that in milk, the problem that about 80 percent of the protein in the bean soup tends to precipitates in the soup arises.
The inventors have conducted researches in the solution of the problem and as a result of the researches, the inventors have found that the precipitation of protein in aqueous solutions of soybean protein due to the addition of calcium salt to the solution can be prevented by subjecting the aqueous solution of soybean protein to heat treatment or alkali treatment so as to denature the soybean protein in the aqueous solution of soybean protein and then adding endpeptidase to the thus pre-treated aqueous solution of soybean protein.